Evans



Aug. 11, 1959 R. D. EVANS HYDRAULIC CLASSIFICATION OF SOLIDS 2 Sheets-Sheet 1 Filed March 11, 1957 w W .0 RV m m0 m h m/ m r 1 6 7 l0 2 w M w m F Aug. 11, 1959 2,899,056

2 Sheets-Sheet 2 INVENTOR.

Raber/ [2 5 0/75 BM 9. MW

AI/omey -duced atthetop of-the column) tend tosettle.

United States Patent Q A Fice 2,899,056 E'Patented Aug. 11, 1959 HYDRAULIC CLASSIFICATION OFSOLIDS Robert D. Evans, Pierce, Fla., assignor to The American Agricultural Chemical Company, New York, N.Y., a corporation of Delaware Application March 11, 1957, Serial No. 645,214

11 Claims. (Cl. 209158) This invention relates to hydraulic sizing or classification of solids, particularly solid material in divided form,

.phatic sands, but the improved apparatus and procedure are also useful for classifying operation with respect to a variety of othermaterials as indicated above.

In a more specific sense, the invention relates to apparatus and procedure, involving so-called hindered settling, for instance by way of improvement of apparatus such as .shown in my Patent No. 2,714,958, issued August 9, .1955.

In general, classificationby hindered settling involves the establishment of an upright columnof liquid to which the feed pulp is supplied at an upper locality and which is also suppliedwith water at thefoot, so as to afford an upward flow of -liquid against .which;the particles of material from the feed pulp (usually intro- Preferably with the aid of local acceleration of:the incoming .water (at the bottom), which is usually ,calledhydraulic or teeter water, the solids reaching the bottom tend to accumulate in a mobile suspension, raising. the effective density of the fluid mass, andindeed building up the suspension through a substantial .vertical: height in the column. The mass is sometimes described; as being in teeter, and the effect of the hindered settling and particularly of the increase in fluid densityithus produced is that only the heavier or larger; particles (i.e. the faster settling particles) will reach the footof the uprighttank. Slower settling particles are hindered. from traveling downward, and in consequence tend to be carried up, for example to the overflow at the very topofthe vessel. By appropriately removing pulp from the foot of the col- ,umn, e.g. just above the locality of introduction of the so-called hydraulic water, a fraction is obtained which consists essentially of higher settling rate solids, usually the coarser fraction, while the line or slow-settlingmaterial is carried away in the overflow.

The present invention is designed to provide improvement in classifying apparatus and procedure, such as described above, for more convenient and efficient operation, for greater simplicity and durability ofconstruction, and for adaptability or adjustability to various conditions and requirements. In particular, the invention is designed to provide apparatus that will be compact and efficient and yet will handle feed pulp having a degree of dilution which might otherwise be troublesome for the operation of hindered settling or might requireunusually large equipment. In another respect, the apparatus is .designed to providev adjustability as to the, degree .of

classification, for example with respect to the size or semi-circular, having a discharge, pipe 22. Feed of pulp settling rate-of particles withdrawn at the overflow.

product, as in a pulp of high solids content.

In cooperation with these and other features, the apparatus is designed to afford improved structure and function of included, to cooperate in controlling the lifeand reliability of the apparatus.

-In the drawings, which illustrate one example of apparatus embodying the invention:

. Figs. 1-A and 1B together'represent a view, chiefly ,in .vertical section butwith certain parts in elevation, of a complete hydraulic classifier, Fig, l-A representing the .main. part of the apparatus and Fig, l-B certain upper :instrumentalities continued above the line aa;

.- Fig. 2, is a plan view of the device but with certain parts, particularly those abovethe main tank, omitted;

'Fig. 3. is a vertical section on line 33 of Fig. 2, of

,the upper part ofthe apparatus of Fig. 1-A; and

Fig; 4 is, a horizontal sectionou line- 44 of Fig. 1-A. Referring to the drawings, which represent a somewhat ..simplified ,and diagrammatic illustration of the equipment,'the main sizer tank, .10 comprises an upright cylin- 25;

drical tank section 11 opening downward into a wider cylindrical pocket or tank section 12 into the bottom of ,which the hydraulic; or teeter water is continuously introduced through acentral pipe .13 fed by a pipe14 having, a controlvalve, 15 and a check valve 16, this pipe system also having anormally-closed valve branch 17 for drain purposes. At the upper part of the tank section 11, the edge 20, occupying about one-half of. the circumference, provides normal overflow means whereby liquid, carrying the finer or slower settling particles of solid overflows into a surrounding launder 21, likewise to,be classified, for example consisting ofmineral par- ,ticles'carried in water, isintroduced into a vertically centr al .portion of the tank section 11 via the inlet passage 24, ,after traversing a preliminary classifying; or,.dewatering device25, of so-called cyclonetype.

Although in many cases a plurality of such cyclone devices may be used, and indeed preferably at least two with, apparatus such as illustrated, being arranged in parallelfor simultaneously handling divided portions of, the feed, a single such means is shown in the drawings for the sake of clarity. The device 25 comprises an upright tank. or vessel26to which, at the upper end, the feed of pulp (which mayhave a relatively low solids content) ,is introduced tangentially through a supply pipe 27. The vvessel 26 being filled with liquid at all times, the thus introduced pulp tends to follow a circular path around the cylindrical wallof the vessel whereby solid particles, and particularly all but the very smallest or slime-type particles tend to move outward, as by centrifugal force. Fromthe bottom of the tank 26, the discharge conduit .28 carries the pulpinto the inlet passage 24 of the main tank 110. A water outlet pipe 30 projects downwardly into the center of the upper part of the vessel 26,, as shown, to withdraw continuously a substantial part of the .waterof the feed pulp, possibly together with very fine particles,.such pipe 30 being connected by a further con- .duit or hose 31 to an appropriate discharge locality, for instance into the launder 21 (Figs. 2 and 3).

At the uppermost part of the tank section 11, an upper tank extension 32 is provided, having a horizontal area representing a substantial'part of the total tank horizontal area,,s ay one-half. A considerable part of the tank sec- .tion' 11 below the upper, portion. 32 is divided by aparti- ,tion' 34, extending, for instance, across a diameter-ofthe tank, this partition 34 being conveniently disposed so as to constitute a lower continuation of upper, adjustable wall or partitioning means generally designated 35 which, with the semi-cylindrical wall, bounds the tank section 32 and extends directly above and alongside the tank portion that is surrounded by the semi-circular overflow 20. The lower edge of the partition plate 34 is conveniently at a locality between one-half and three-fourths of the height of the overflow 20 above the general region of the inlet of hydraulic water at the bottom of the tank 10, preferably at a point two-thirds of the distance from the hydraulic water inlet to the overflow.

The adjustable wall or partitioning means 35, which together with the plate 34 provides an adjustable partition for the upper part of the tank dividing it into two upper levels, comprises a pair of flanged channels or slots 36, 37 extending vertically at opposite sides of the uppermost tank wall 32, i.e. at the vertical edges of the latter, and arranged to receive a plurality of slats or narrow plates 38 with their long edges in successively abutting position so as to build up a wall or partition. It will be understood that these plates fit in the channels 36, 37 and abut each other with suflicient closeness as to provide essentially water-tight contact to contain the liquid in the upper section 32 to the level, represented by the uppermost slat .edge, e.g. as shown at 39. It will be seen that by inserting or removing slats, the height of the wall 35 is adjustable, from a level substantially below the normal overflow edge 20, to levels at various heights above such edge.

A separate launder or channel 40 extends across the tank portion having the edge 20 and may slope down slightly at each side (as shown) to receive overflow from the adjustable wall edge 39, i.e. the upper overflow, and discharge same into an appropriate locality, which may be the same collecting launder 21.

For withdrawal of a product of high settling rate solids from the foot of the teeter column constituted in the tank 10, suitable means are provided. Although simple cone or plug valve devices extending down from a lower part of the pocket 12 can be used, the apparatus very preferably includes siphon discharge means of the character disclosed in my Patent No. 2,714,958, granted August 9, 1955, to which reference may be had for further details of structure and function. Essentially such siphon discharge comprises a long upright pipe 42 having an enlarged lower section 43 into which siphon-assisting water is continuously supplied through a valved inlet pipe 44, to flow up into the pipe 42, the lower part 43 opening downwardly at a region near the bottom of the hindered settling column, viz. in a vertical central or lower region of the pocket 12. At its upper end, spaced substantially above the normal overflow, the pipe 42 has a connecting chamber 45 from which a discharge pipe 46 extends laterally and downwardly to a locality below and preferably well below the overflow level 20. For instance, the pipe 46 may there open into discharge pocket 47 from which the product pulp is withdrawn by an outlet pipe 48.

Although hydrostatic control means of the type shown in the illustrated examples of my Patent No. 2,714,958,

with hydrostatic conduits opening directly into the liquid of the tank 10, may be effectively employed for controlling the operation of the siphon discharge 4246, the drawings illustrate an improved embodiment of such means. For instance, a long vertical hydrostatic pipe 50 extends to the lower pocket 12 of the apparatus, being there closed by a flexible diaphragm structure which is exposed to the liquid at the bottom of the teeter column. Specifically the flexible diaphragm may consist of a long flexible, thin wall, somewhat resilient tube 51, of rubber or the like, having a rigid top connected to the rigid conduit 50 and a rigid bottom closure 52, with supporting rods (not shown) between top and bottom if desired. At an adjustable locality above the connecting chamber 45 the conduit 50, through a flexible tube 54, opens into the bottom of a control chamber 55 which preferably has a transparent wall for observation and which encloses a float 56 having an upper needle-shaped or cone-like projection 57. The projection 57 constitutes a needle valve with an upper conduit 58 into which it projects, so that when the float 56 rises the needle or cone valve 57--58 is closed. The conduit or nipple 58 is connected by a flexible tube 59 into the top of the chamber 45. A thin highly flexible diaphragm 60 seals the space within the housing 55 between the top of the housing side wall and the top of the float, so that the region above this diaphragm is filled with air, by reason of communication with the atmopshere through the passage 61, while liquid in the chamber is maintained below the diaphragm.

From one side of the housing or chamber 55, a flexible conduit 63 extends to a small, open-type reservoir 64 supported (as by means not shown) at a predetermined high locality. The control chamber 55 is carried by a bracket 65 adjustably mounted on a suitable, fixed supporting rod 66. The system comprising the lower diaphragm chamber 51, rigid hydrostatic tube 50, tube 54, the main portion of chamber 55, tube 63 and reservoir 64 is supplied with an appropriate liquid, which is preferably of non-corrosive character and may be water, or in some cases other liquids, for example having a density not appreciably greater than the density of water where aqueous pulps are, as usually, to be handled in the classifying apparatus.

The discharge control means functions on the basic principles explained in my cited Patent No. 2,714,958, to eifectuate operation of the siphon when hindered settling action is occurring for desired accumulation of coarser or higher settling rate solids at the foot of the column, e.g. in the pocket 12. When hindered settling is thus occurring as desired, the presence of the solids in teeter near the bottom and throughout a considerable upper part of the column increases the fluid density of the liquid and correspondingly the fluid pressure at the bottom, i.e. in the pocket 12. Hence a column of water, such as the liquid in the hydrostatic conduit 50, containing no solids, will be displaced by compression of the diaphragm 51 and will rise above the normal overflow 20 to a substantially higher level, e.g. to or beyond the top of the chamber 55. The vertical position of the chamber 55 is adjusted so that when the desired pressure is reached at the foot of the teeter column, as represented by the desired accumulating of solids to be separated, the corresponding liquid displacement causes the float 56 to rise and close the cone valve 57-58. The uppermost bend of the siphon 4246 (at 45) having been previously vented to the atmosphere through the tube 59, is now closed. Aided by the continuing flow of supplemental water from the pipe 44, the hydrostatic pressure carries water promptly to fill the pipe 45 starting siphon action, whereupon pulp including the desired, separated solid particles is continuously carried up the pipe 42 and through the siphon to discharge as product via the means 47, 48. Should the classifying action be inadequate, the fluid pressure in the pocket 12 falls, correspondingly reducing the pressure on the diaphragm 51 and causing the float 56 to drop. The cone valve 5758 then vents the siphon to the atmosphere, interrupting siphon flow of pulp. Thus the described means automatically controls the siphon operation to effectuate it only when desired settling conditions are occurring, i.e. for separation of the feed solids into the desired high settling rate fraction.

Whereas in previous devices it has been conventional to introduce the hydraulic or teeter Water at the foot of the column through a so-called constriction plate, which would in the apparatus shown be a plate extending entirely across a lower region of the pocket 12, having a large multiplicity of perforations (the water being supplied under pressure to the space below such plate), and although such constriction plate can be used with other features of the improved device shown, the drawings illustrate a simplified arrangementforsupplying this fashion, with the aid of distribution of a major part of it outwardly and upwardly around and beyond. the edges of the plate 70, and with some upwardjets directly through the perforations 71, effective upper flow of liquid is provided for the hindered .settling action. The incoming water thus enters at a considerable velocity, for cooperation in establishing teeter conditions, it being found that such instrumentalities afford effectively constricted water supply and satisfactory distributionof upwardly introduced water, for the stated purpose.

It will be understood that a plurality, e.g. two, three or more, of the siphon discharge means may be employed, each with its separate hydrostatic control. For

.simplicity of illustration, the drawings merely show the lower portion of another siphon discharge system, as by .the siphon sections 42a, 43a and the hydrostatic diaphragm 51a and conduit 50d.

The operation of the apparatus and the advantages of various novel features are now to be further described. For efiicient operation of a hindered settling column of .the simple vertical type shown in the drawings, a pulp feed which is substantially steady in rate of flow and which is reasonably constant in solids. content or dilution, is relatively important; if there are large amounts of water with the feed or if there are sudden large surges of feed, the tank overflows very heavily, the teeter effect is substantially lost and there is insufficient separation of .solids by settling rate, eitherunder hinderedor free- .settling action. In general, the solids feed, e.g. as determined in the. case of particles of phosphate rock, should be such that the pulp supplied tothe column (preferably at a locality at least about one-third of'the ,distance below the normal overflow, to avoid too much loss, of desired coarseparticles) contains at. least about 40% solids by weight, and preferably 60% to 70%.

It will be remembered that in the operation of a hindered settling column, the dilution effected by the hydraulic water rising from the bottom is considerable. The device. 25 cooperates to insure or maintain desired pulp feed in the hindered settling system, even where the solids content of the pulp actually received may be considerably lower than desired or where there maybe changes in the flow of feed occasioned by variations in dilution. ,Thus by the cyclone action, involving the circular flow initiated at the top of the tank 26, the greater part of the particles are carried to the wall of the device .25 and travel downwardly to the bottom fordischarge ,throughthe passage 28. Under the pressure of the sup- ,plied liquid, the pipe 30 thus removes a considerable amount of water which is freed from the desired solid particles or which contains only a small proportion of fine particles, slimes or the like. In consequence, a substantial steady flow of pulp with the desired, moderate or high solids content is introduced into the main tank In other words, the

Where the feed pulp consists of a reasonably steady fiow of solids accompanied by wide fluctuations in water content. The, excess water is, removed by the cyclone over- I flow 30, 31, leaving a steadyrflow of relatively dewatered solids to the hindered settling column by way of the cyclone underflow 28.

It will be understood that the cyclone device 25 is tank It) and is preferably situated so" that a substantial part of its extent rises above the normal overflow, 20, i.e.

to avoid undueloss of pulp through the siphon overflow drawing diagrammatically shows a somewhat lessened relation, for the sake of compactnessof illustration.

-The adjustablepartition and wall structure constituted by the means 34, 35 affords flexibility in predetermining the classifying action of the apparatus. Forexample,

- if all of the slats 38 are removed, the device functions as if there were no partition 34 or upper. section 32. The overflow level is wholly determined by the edge '20,,and the liquid rise velocity through the upper part of the column, e.g. above the inlet 24, is nearly constant over the entire cross-sectional area. In such case (since the upper edge of the partition 34 is several inches below the level 20) the rise velocity has a minimum value for the apparatus, and the solids overflowing at the top. represent only a relatively fine-fraction. If some slats 38 are inserted, for example to raise the level in the section 32,

several inches above the edge 20,.the upper portion of the tank is then dividedinto two sections, with. a larger rise velocity of liquid in the section terminated by the edge 20, i.e. the normal overflow region, than in the regionto the right of the plate'34 as seen in Fig. l-A. Where, for example, all of the illustrated slats are inserted, this disparity in rise velocities .in the two sections increases, essentially to the point Where the rise velocity in;the lefthand or normal overflow section may be doubled and where it, may fall to. a very low or even zero value in the section32. By so adjusting the effective rise velocity in the upper part of the tank, largerproportions of coarser or faster-settling particles may be removed vwith the overflow, i.e. the principal overflow at the edge. 20. In consequence, the nature and extent of solids classification for removal of highest. settling rate product (at the foot of the column) is adjusted with the adjustment of the wall constituted by the slats 38. When the slats are inserted to provide a normal overflow section of increased rise velocity, thev proportion of solids less than the finest which travel to the, overflow is increased, and in consequence the inclusion of such solids,,along with the coarsest or1fastest-settling in. thesiphon discharge product, is reduced.

Thus by the adjustable partition means the rise velocity in the upper part of the hindered settling column can be varied, e.g. to variouspredetermined values, and the nature of fractionation, and particularly the particle size characteristics of, the siphon discharge product and overflow product respectively, can be modified.

As explained, there may be some-overflow from the uppermost column section 32, largely consistingof water with only the veryfinest solids. Although in some cases it may be desired to conduct thisoverflow toaseparate locality (as where the tailings from the normal over- .flow 20 are recovered for a special use),.the drawing for from 25% to preferably 50% (or more) larger thanthat of the upper tank section 11,.affords certain special advantage. It ,provldes a region of .low rise velocity, at the foot of the teeter or hindered settlingcolumn, in

.which :the sized particlesv may settle and compact prior to their discharge through the siphon conduit system As a consequence less teeterywater is lost of relatively high solids content, for example 55% or .conveniently ,located, asshown, alongside of the main i substantially higher (by weight) can be obtained. This settlingpocket also provides space for the enlarged'por- 'tions of devices that are disposedwithinihe*tank 10,e.g.

in various cases, for example where their special cooperative effects are not needed. Likewise other forms of instrumentalities, for example as previously provided for the introduction of teeter water or for the control of siphon discharge, may be employed.

The general operation of the apparatus is believed implicit in the foregoing description. Feed pulp is supplied continuously to the cyclone device 25, which in effect dewaters it as necessary, and the resulting continuous feed to the column in the tank 11 maintains the desired supply of solids to be classified. Hindered settling conditions are continuously maintained by the upward flow of water from the bottom of the pocket 12, and when maintained, the siphon discharge, under control of the device including the float 56, removes the desired fraction of high-settling rate material. From the overflow at the upper edge 20, the finer or lower settling sizes are removed, with considerable volume of water. Where the adjustable wall is included and set for establishment of a relatively quiet upper section of liquid, the effective rise velocity of the upper portion of the teeter column, i.e. to the left of the partition 34 in Fig. l-A is correspondingly increased with a desired predetermined effect on the separating action as explained. The entire apparatus is desirably continuous in function, permitting considerable variation in feed characteristics and afiording a greater flexibility of presetting, by the adjustable partition as well as by the siphon discharge control, to obtain a specific result. While dimensions and proportions may vary widely, one useful example involved a steel tank having an upper section about 12 feet high from the lower pocket 12 to the overflow 20 and a diameter of about 4 feet. The total height of the pocket 12 was about 4 feet, with a diameter of approximately 6 feet. As stated, the size and arrangement of the apparatus will depend, in a given case, upon the requirements of use, including the volume of material to be handled.

It is to be understood that the invention is not limited to the specific structures shown but may be embodied in other forms without departure from its spirit.

I claim:

1. Hydraulic sizing apparatus comprising, in combination, upright tank means adapted to contain a column of liquid and having overflow means at a predetermined upper level thereof, means opening into the tank means at a position therein which is spaced below the top thereof for introducing feed pulp of particles to be sized, means at the foot of said tank means for introducing a flow of liquid to effectuate hindered settling of solid par- -ticles within the liquid of said column, for accumulating faster-settling particles at the foot of the tank means, and siphon discharge means opening at its lower end into the tank means at said foot thereof and extending upward therefrom for removal of pulp of particles accumulated by hindered settling, said tank means including a horizontally enlarged tank portion at the foot thereof and surrounding said lower end of the siphon discharge means and said liquid introducing means, to provide a lower rise velocity of liquid in said portion than in tank regions above the same.

2. Hydraulic sizing apparatus comprising, in combination, upright tank means adapted to contain a column of liquid and having overflow means at a predetermined upper level thereof, means opening into the tank means at a position therein which is spaced below the top thereof for introducing feed pulp of particles to be sized, means at the foot of said tank means for introducing a flow of liquid to effectuate hindered settling of solid particles within the liquid of said column, for accumulating faster-settling particles at the foot of the tank means, and siphon discharge means opening at its lower end into the tank means at said foot thereof and extending upward therefrom for removal of pulp of particles accumulated by hindered settling, said tank means including a horizontally enlarged tank portion at the foot thereof and surrounding said lower end of the siphon discharge means and said liquid introducing means, to provide a lower rise velocity of liquid in said portion than in tank regions above the same, and said liquid introducing means comprising conduit structure opening through the bottom of said enlarged tank portion and plate means having a diameter equal to a minor fraction of the diameter of the said tank portion, disposed over said conduit structure for deflecting the introduced liquid to disperse it upwardly in the tank.

3. Hydraulic sizing apparatus comprising, in combination, upright tank means adapted to contain a column of liquid and having overflow means at the top, means at the foot of said tank means for introducing a flow of liquid to effectuate hindered settling of solid particles within the liquid of said column, and means for introducing a feed pulp of solid particles to be classified, including supplemental upright vessel means having a tangential inlet at the top for establishing a circular current of feed pulp in said supplemental tank means, to urge solid particles in the feed toward the wall of said tank means, means extending into the center of the upper part of said supplemental vessel means for withdrawing a portion of liquid therefrom, which is reduced in solids content by said circular current, means at the foot of said supplemental vessel means and opening into the upright hindered settling tank means at a locality spaced below the top thereof, for conducting feed pulp of reduced water content into said hindered settling tank means, for classifying action thereon, and siphon discharge means opening at its lower end into the tank means at said foot thereof and extending upward therefrom for removal of pulp of particles accumulated by hindered settling, said tank means including a horizontally enlarged tank portion at the foot thereof and surrounding said lower end of the siphon discharge means and said liquid introducing means, to provide a lower rise velocity of liquid in said portion than in tank regions above the same.

4. Hydraulic sizing apparatus comprising, in combination, upright tank means adapted to contain a column of liquid and having overflow means at the top, means at the foot of said tank means for introducing a flow of liquid to effectuate hindered settling of solid particles within the liquid of said column, siphon discharge means comprising a conduit having an inlet opening near the foot of said tank means and extending upwardly to an upper locality above said overflow means and from said locality downwardly to a discharge locality below said overflow means and outside the tank means, said conduit being adapted to withdraw accumulated pulp of faster settling particles from the foot of the tank means while slower settling particles are discharged at the overflow means, said conduit having a control opening therein at its said upper locality and valve means shiftable selectively to close said control opening for eifectuation of siphon discharge action and to open said control opening to the atmosphere for interrupting siphon discharge action, pressure responsive means, including structure extending into said tank means to a position near the aforesaid inlet opening of the conduit to sense pressure in the fluid material near said inlet opening, for operating said valve means to keep said valve means closed for siphon discharge when the accumulated faster settling solids maintain the aforesaid fluid pressure at greater than a predetermined value and to open the valve means for interrupting siphon discharge when there is insufficient accumulation of faster settling solids to provide said greater pressure, and means for introducing into the tank means a feed pulp of solid particles to be classified into the aforesaid faster settling and slower settling particles, including supplemental up- 9 right vessel means having a tangential inletat the top for establishing a circular current of feed pulp in said suplemental vessel means, to urge solid particles in the feed toward the wall of said vessel means, means extending into the center of the upper part of said supplemental vessel means for withdrawing a portion of liquid therefrom, which is reduced in solids content by said circular current, and means at the foot of said supplemental vessel means and opening into the upright hindered settling tank means at a locality spaced below the top thereof, for conducting feed pulp of reduced liquid content into said hindered settling tank means, for classifying action thereon, said supplemental vessel means and its said tangential inlet and its said liquid withdrawing means and pulp conducting means being constructed and arranged for effectuating said reduction of liquid content of the feed pulp to prevent excess liquid in the feed from impairing the hindered settling action in the tank means and the desired accumulation of faster settling particles at the foot of the tank means.

5. Hydraulic sizing apparatus comprising, in combination, upright tank means adapted to contain a column of liquid and having overflow means at a predetermined upper level thereof, rneans at the foot of said tank means for introducing a flow of liquid to effectuate hindered settling of solid particles within the liquid of said column and to maintain continuous rise of liquid in the tank means to said overflow means, means including upper tank Wall structure and cooperating adjustable partition wall means across the tank means for providing an upper extension of the tank means above the aforesaid level, partitioned from the overflow means, said partition wall means cooperating with the tank means to provide a narrowed upper portion in the tank means below said overflow means, said upper extension and said narrowed portion cooperating to maintain a higher rise velocity of liquid rising in the narrowed portion to said overflow means than in liquid below said narrowed portion, said partition wall means being adjustable in height for adjusting said last-mentioned rise velocity to vary the sizing action of the apparatus, means for introducing into the tank means a feed pulp of solid particles tobe classified, including supplemental upright vessel means having a tangential inlet at the top for establishing a circular current of feed pulp in said supplemental tank means, to urge solid particles in the feed toward the wall of said tank means, means extending into the center of the upper part of said supplemental vessel means for withdrawing a portion of liquid therefrom, which is reduced in solids content by said circular current, and means at the foot of said supplemental vessel means and opening into the upright hindered settling tank means at a locality below the partition wall means, for conducting feed pulp of reduced water content into said hindered settling tank means, means extending into the center of the upper part discharge of solid particles from the foot of the tank means, as accumulating by hindered settling.

6. Hydraulic sizing apparatus comprising, in combination, upright tank means adapted to contain a column of liquid and having overflow means at a predetermined upper level thereof, means at the foot of said tank means for introducing a flow of liquid to effectuate hindered settling of solid particles within the liquid of said column and to maintain continuous rise of liquid in the tank means to said overflow means, means including upper tank wall structure and cooperating adjustable partition wall means across the tank means for providing an upper extension of the tank means above the aforesaid level, partitioned from the overflow means, said partition wall means cooperating with the tank means to provide a nar rowed upper portion in the tank means below said overflow means, said upper extension and said narrowed portion cooperating to maintain a higher rise velocity of liquid rising in the narrowed portion to said overflow means than in liquid below said narrowed portion, said partition wall means being adjustable in height for adjusting said last-mentioned rise velocity to vary the sizing action of the apparatus, means for introducing liquid pulp of solids to be sized into the tank means below the partition wall means, and means for discharge of solid particles from the foot of the tank means, as accumulating by hindered settling.

7. Apparatus as defined in claim 6 wherein the adjustable partition wall means comprises a permanent partition wall across the tank means below the aforesaid overflow means, partition section-receiving means extending upwardly from said permanent wall along said upper tank wall structure, and a plurality of mutually abutting, ve'rtically aligned, removable partition sections received in said section-receiving means.

8. Apparatus as defined in claim, 7 wherein the section-receiving means comprises a pair of channel structures at opposite sides of the upper tank wall structure, the partition sections being slats each having its ends disposed in said channel structures.

Hydraulic sizing apparatus comprising, in combination, upright" tank means adapted to contain a column of liquid and having overflow means at the top, means at the foot of said tank means for introducing a flow of liquid to effectuate hindered settling of solid particles within the liquid of said column, means for introducing a feed pulp of solid particles to be classified, into the tank means, and siphon discharge means opening at its lower end into the tank means at said foot thereof and extending upward therefrom for removal of pulp of particles accumulated by hindered settling, said liquid introducing means being disposed below the siphon discharge means and said liquid introducing means comprising conduit structure opening through the bottom of the tank means and plate means within the tank means, having a diameter equal to a minor fraction of the diameter of said tank means around it, disposed over said conduit structure for deflecting the introduced liquid to disperse it upwardly in the tank.

10. Hydraulic sizing apparatus comprising, in combination, upright tank means adapted to contain a column of liquid and having overflow means at a predetermined upper level thereof, means at the foot of said tank means for introducing a flow of liquid to effectuate hindered settling of solid particles within the liquid of said column and to maintain continuous. rise of liquid in the tank means to said overflow means, means including upper tank wall structure and cooperating adjustable partition wall means across the tank means for providing an upper extension of the tank means above the aforesaid level, partitioned from the overflow means, said partition wall means cooperating with the tank means to provide a narrowed upper portion in the tank means below said overflow means, said upper extension and said narrowed portion cooperating to maintain a higher rise velocity of liquid rising in the narrowed portion to said overflow means than in liquid below said narrowed portion, said partition wall means being adjustable in height for adjusting said last-mentioned rise velocity to vary the sizing action of the apparatus, means for introducing into the tank means a feed pulp of solid particles to beclassified, including supplemental upright vessel means having a tangential inlet at the top for establishing a circular current of feed pulp in said supplemental tank means, to urge solid particles in the feed toward the wall of said tank means, means extending into the center of the upper part of said supplemental vessel means for withdrawing a portion of liquid therefrom, which is reduced in solids content by said circular current, and means at the foot of said supplemental vessel means and opening into the upright hindered settling tank means at a locality below the partition wall means, for conducting feed pulp of reduced water content into said hindered settling tank means, for classifying action thereon, and siphon discharge means opening at its lower end into the tank means at the foot thereof and extending upward therefrom for removal of particles accumulated by hindered settling, said tank means including a horizontally enlarged tank portion at the foot thereof and surrounding said lower end of the siphon discharge means and said liquid introducing means, to provide a lower rise velocity of liquid in said portion than in tank regions above the same, and the aforesaid liquid introducing means being disposed below the siphon discharge means and comprising conduit structure opening through the bottom of said enlarged tank portion and plate means having a diameter equal to a minor fraction of the diameter of the said tank portion, disposed over said conduit structure for deflecting the introduced liquid to disperse it upwardly in the tank.

11. Hydraulic sizing apparatus comprising, in combination, upright tank means adapted to contain a column of liquid and having overflow means at a predetermined upper level thereof, means at the foot of said tank means for introducing a flow of liquid to effectuate hindered settling of solid particles within the liquid of said column and to maintain continuous rise of liquid in the tank means to said overflow means, means including upper tank wall structure and cooperating adjustable partition wall means across the tank means for providing an upper extension of the tank means above the aforesaid level, partitioned from the overflow means, said partition wall means including a vertical partition member cooperating with the tank means to provide a narrowed upper portion in the tank means below said overflow means, said upper extension and said narrowed portion cooperating to maintain 'a higher rise velocity of liquid rising in the narrowed portion to said overflow means than in liquid below said narrowed portion, said partition wall means being adjustable in height for adjusting said last-mentioned rise velocity to vary the sizing action of the apparatus, means for introducing liquid pulp of solids to be sized into the tank means at a locality spaced from said narrowed portion, and means for discharge of solid particles from the foot of the tank means, as accumulating by hindered settling.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,899,056 August 11, 1959 Robert D a Ev ns of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 9, line 55, for "means extending into the center of the upper part" read for classifying action thereon, and means for "0 Signed and sealed this 3rd day of May 1960o (SEAL) Attest:

KARL Ho AXLINE Attesting Officer ROBERT C. WATSON Commissioner of Patents 

